双代号网络图中节点表示()
A.工作
B.工作的开始
C.工作的结束
D.工作的开始或者结束
参考答案:D
(74) systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and (75) on the disk, and controlling peripheral devices such as disk drives and printers.
A.contents
B.diectories
C.directions
D.direct
金属导体的电阻值随温度的升高而()。
A.增大
B.不变
C.减小